1. Field of the Invention
This invention relates to a system for aiding an operator in executing step by step procedures during the operation of a complex process. More specifically, this invention relates to a display system that provides an overview of the outcome of executing the criteria for sequentially processing the steps of a method for controlling a complex process.
2. Related Art
Operation of a complex process facility requires the assimilation of a large amount of data and evaluation of the status of the process and the various component systems from those data, and informed, decisive action based upon such evaluation. While much of the operation of a modern complex process facility is automatically controlled, overall supervision of the facility is always the responsibility of a human operator.
Typically, formal written plant operating procedures under either normal or emergency conditions are developed by experienced specialists. Such “paper” procedures have been used for many years, particularly in facilities such as nuclear power plants. Recently, interactive computer-based systems for aiding the operator in the execution of complex operating procedures have been developed. For instance, U.S. Pat. No. 4,803,039 discloses such a system in which the sequential steps of a procedure are presented to the operator on a display screen. The system automatically monitors the appropriate parameters relevant to the steps of the procedure. Where conditions required by certain steps are not satisfied, alternatives are offered to the operator. In either case, a response is required from the operator before the system advances to either the next step or a step in another procedure commanded by the operator. U.S. Pat. No. 4,815,014 describes a related system that requires verification that an operator action has, in fact, been taken before it will advance to the next step in the procedure. The operator, however, may override the requirement for such verification. The interactive systems described to this point were hard coded, therefore requiring the writing of new code and verification of all of the software when any changes were to be made, including altering of reference values of the various parameters. U.S. Pat. No. 5,553,304 overcomes this particular problem by describing the use of a relational database to generate and store equations representing the various sequential steps in the procedures. With such a system, changes can be made in the pertinent parameter values and even in the procedures themselves without the necessity to generate new code and verify the codes so generated.
However, the interactive computer-based systems for assisting in the execution of complex process procedures described in the foregoing patents require manual input by an operator to advance to a next step. They also only provide the ability to have one procedure active at a time. If the operator accepts a recommendation to transfer to another procedure, the exited procedure becomes inactive.
With the complexity of process facilities, such as especially nuclear power plants, increasing there is a particular need for an improved system and method for accurately and expeditiously executing procedures in a complex process facility. U.S. Pat. No. 5,881,115 satisfied this need by providing a supervisory, sequential controller interface for automatically sequencing through the sequential steps of such procedures. The supervisory, sequential controller also provides an operator interface presenting to the operator a representation of the sequential steps as they are executed, which permits the operator to selectively assume manual control of the procedures. A relational database forms the core of the system and is used to generate equations representing the sequential steps, which are then automatically or manually executed.
Starting conditions for automatic execution of the procedures are established so that upon satisfaction of these conditions, the procedure is initiated automatically. Stop conditions for automatically stopping a procedure can also be established.
Some of the procedural steps generate control signals which result in modification of process conditions, e.g., the opening and closing of valves, the stopping or starting of pumps, etc. Such control signals are automatically generated by a procedure which is running automatically. Some procedures call for verification that the control signal has been effective before advancing to the next step. In some instances, this may take some time. If the condition is not satisfied, the step is violated and the automatic sequencing will terminate, requiring operator intervention. A suitable time delay is provided to allow the command signal to take effect so that the process may continue automatically. Time delays are also programmed into some of the steps of the procedure so that the operator may follow the sequence of steps during automatic execution.
The system described in U.S. Pat. No. 5,881,115 also includes the ability to sequence through the steps of multiple procedures simultaneously and make available to the operator, through the operator interface, representations of the sequential steps of each of the multiple procedures as they are being executed. An important feature of the system is the operator interface which is comprised of two parts: An executive interface and a procedure interface. The executive interface allows the operator to view and select the status of each of the procedures. The executive interface also allows the operator to globally select automatic sequencing so that as the start conditions are met for the various procedures, they are automatically initiated. The procedure interface presents a representation of the current step of the selected procedures. The current steps of multiple procedures can be presented in separate windows.
While the system that evolved out of the inventions described in U.S. Pat. Nos. 4,803,039, 5,553,304 and 5,881,115 contributed significant advances to the control of very complex processes, automatic control of those processes created a need for the operator to have a greater understanding of the criterion employed for advancing each of the steps of the process and of the satisfaction of the criterion, and verification that the commands issued as a result of satisfaction of the criterion have been carried out for each of the steps of the process, without sacrificing a global view of the steps of the procedures that are running.
There is a particular need for such a system that readily enables the operator to assimilate that information at one time for substantially all the related procedures that are running for that process.